1. Field of the Invention
The present invention is to provide a multifunction passive and continuous fluid feeding system for external systems, wherein the system is capable of performing multifunction fluid feeding tasks for automatic operation, continuous fluid feeding, and control based on various fluid-feed requirements by the external systems.
2. Description of the Background Art
In the realm of conventional fluid feeding techniques, the most commonly seen practice is to employ pumps with adequate head as the driving component to inject the feed-fluid to the external systems. An example of this practice is the high-pressure water injection system of nuclear power plants, which automatically activates at time of depressurization during incidents to inject coolant into reactor core for removing the decay heat generated therein. Another practice is to employ accumulators as the driving component to inject fluid therein by the high-pressurized gas contained therein to the external systems. Examples of these conventional practices include the inventions disclosed in U.S. Pat. Nos. 5,845,713, 5,845,714, and 6,006,840, relating to the roof spray fire extinguishing system employing nitrogen cylinders as pressure supplying source to press the nitrogen gas into the tanks stored with extinguishing liquid, transmitting the extinguishing liquid through pipe lines on the roof into the sprinklers on the ceiling to put out a fire. Also, for the above-mentioned example of the water injection system of nuclear power plants at time of depressurization during incidents, it can automatically inject the pre-pressurized water to the reactor core, when the system pressure lowers to the preset level for activating to remove the decay heat generated therein. Furthermore, the fuel supply systems for automobile engines as disclosed in U.S. Pat. Nos. 6,273,067, 6,035,829, 5,727,525, and 6,120,711, employ high-pressure pumps to-first transmit the fuel contained in the fuel tank into pressurized accumulator for storage, and then control the on-off periods of the fuel spray nozzles in each cylinder by sequential ignition of the cylinder strokes, enabling the fuel-feed into the combustion chamber by pulse in a cyclic manner.
When the above-mentioned conventional fluid-feed practices are applied in systems with high pressure and high temperature, or large scaled industrial systems, the costs of investment solely made on the high-head pumps will be astonishing. Besides, in any power plant or factory facility, when emergency incidents occurs, the major power supply is usually shut down first, with only the emergency power supply system left to provide lower rating power for use by minimum lighting and instrumentation. To maintain normal fluid-feed functioning, the installation of reliable emergency power supply system of higher rating is needed; otherwise, more severe damages may occur due to the failure of fluid-feed function. In addition, the cooling practice by using accumulators to inject water into the reactor core may not, in some incidents, be able to bring the pressure of the system smoothly down to the triggering point preset for the accumulator to activate water injection, for instance, when there is a break of less than 2 inches in diameter at the cold leg, or when loss-of-coolant incidents occur, resulting from small break due to fracture on the instrumentation pipe lines, or, with the low depressurization rate, the water injection may still be grounded to almost a halt, even though the water injection system may have been activated when the preset triggering point is reached, causing poor cooling results of the reactor core.
Furthermore, in the fields of on-line reaction control in some chemical continuous processes and other industrial or academic researches, it is not difficult to see the needs of the feed fluid flow rate varying with the changes of one or more key parameters of the external systems. As a result, even if the systems are equipped with the above-mentioned expensive pumps, it does not necessarily ensure the accuracy of fluid feeding function. For instance, a small pilot plant can run simulation tests in advance of the actual operations of fluid feeding at different pressure levels in the prototypical plants, with the prototypical plants having preset the pumps to drive the fluid feeding, or, namely, the feed fluid flow rate is to vary at different pressure levels throughout the process, according to the performance curve of the fluid feeding pumps. Hence, to accurately simulate the feed fluid flow rate in the pilot plants will be critical to successful simulation of the actual processing of the prototypical plant. However, when a pilot plant directly uses pumps to simulate the feed fluid flow rate, it needs to overcome the inevitable extreme differences between the two sets of performance curves due to the significant specification differences of the two pumps. Even if the pilot plant can be equipped with an additional set of sophisticated mechanism for the pump to automatically adjust its rotation rate, the pump is still difficult to fully meet the requirement of accurate fluid feeding simulation. The above mentioned problems commonly seen during the fluid feeding simulation tests in pilot plants should be solved by simple, economic, and reliable methods.
Moreover, the feed fluid supply system currently applied in fire engines also uses high-head and high-pressure pumps as the driving component which injects the extinguisher in the feed fluid tanks to the fire scenes. As a series of pumps in the above mentioned application are connected for purpose of enhancing the head so as to achieve effectiveness by increasing the injection range and height, particularly those designed for high-rise fire fighting operation, and outside of consideration of public safety at the fire scene, power supply is shut down prior to fire fighting operation. Therefore, fire engines have to be equipped with built-in diesel electric sets for supplying power to its own pumps, making the power equipment for driving fluid feeding on the fire engines rather heavy-weighted and bulky. Apart from the noise of the pumps that deteriorates the communication quality at the fire scene, with the limited space available on the vehicles, they squeeze out the amount of extinguisher that can be carried along, and as a result, it is unfavorable for the mobility of the fire engines, while increasing difficulty for fire fighting operation in small alleys. The complicated electric equipment installed on the vehicle also makes it inconvenient to do regular maintenance and performance tests. In case when an effective fluid feeding mechanism is lacking before the extinguisher runs out, the function of fire extinguishing will be interrupted or gone.
To overcome the deficiencies of the above-mentioned conventional practices, an object of the present invention is to provide a multifunction passive and continuous fluid feeding system for external systems, including a storing and transmitting component, a measuring and regulating component, and a control unit, characterized by pressurizing from above the fluid level surface of the feed fluid tank by high-pressure gas supply source to build up the passive fluid-feed supplying function, performing the fluid-feed measuring and regulating through the flow meter and flow control valves installed on the transmission pipe lines connecting to the external systems, fulfilling function of continuous fluid feeding by switching between two fluid-feed tanks, and combining the feed fluid requirements of the external systems through the control unit to achieve the multifunction fluid-feed of automatic operation, continuous fluid feeding, and flow rate controlling.
The automatic continuous fluid feeding system of the present invention utilizes cheap and reliable high-pressure gas supply to take the place of the conventional expensive high-head high-pressure pumps and the high rating power suppliers. Not only does it carry the functionality of conventional fluid feeding system, but also the potentials of extended applicability into various systems or industrial fields, due to the easiness of its coping with various fluid-feed requirements by external systems. Apart from solving the problem of continuity deficiency of the conventional fluid feeding systems which results from at least one of the accumulators operable independently as sources of feed fluid supply, the adding of automatic switching control mechanism to the feed fluid tanks allows significant down-scaling of the feed fluid tank volume and the overall fluid feeding system. Furthermore, the adding of control unit not only allows continuous fluid feeding by automatic switching through measuring and regulating components. It also demonstrates its functionality with high accuracy in controlling flow of feed-fluid. Accordingly, the present invention can easily surpass the difficulties by the conventional systems, while improving their reliability and functionality. Therefore, from the viewpoint of risk management, the present invention is particularly applicable, when fluid feeding is required over a long period of time, or fluid feed system stays normally in reserve but activates its fluid-feed function at time of emergency, or accurate control over feed fluid flow rate is required based on various fluid-feed requirements by external systems.
In summary, the object of the present invention is to provide a kind of multifunction passive and continuous fluid feeding system, which is of simple structure and high reliability, for external systems, wherein the system is capable of performing multifunction fluid feeding skills for automatic operation, continuous fluid feeding, and flow rate control based on various fluid-feed requirements by the external systems. Besides being highly reliable, capable of lowering disaster risks, the present invention has the advantages of cost effectiveness, energy saving, environmental friendliness, and conveniences for maintenance and performance testing, as well as the potentials of extended applicability into various fields. The application fields of the present invention at least include the following: the fluid feeding or cooling systems as emergency back-up system for industrial purposes, the fluid feeding systems for high-temperature and high-pressure boilers, on-line inputs proportion control in chemical continuous processes, safety water injection system within full range of pressure variation in nuclear reactors, feed-water and level controlling system for steam generators, fluid feeding simulation tests in pilot plants, and various types of public safety and fire extinguishing systems.